(1) Manual Method

In order to evaluate the satisfactory level of a particular school service provided for students, a survey was conducted in schools for collecting students' satisfactory ratings on the service provided in three years of 2003, 2004 and 2005. The rating scale ranges from 0 to 10, with 0 not satisfaction and 10 extreme satisfaction. Suppose the satisfactory levels follow a normal distribution. The survey data were collected and then processed by SPSS. The SPSS descriptive statistics are shown in below Table 1.

Table 1:Descriptive Statistics

	N	Mean	Std. Deviation	Variance
Satisfactory level in 2003	18	6.4389	1.48369	2.201
Satisfactory level in 2004	18	6.3889	.75994	.578
Satisfactory level in 2005	18	7.6167	1.38744	1.925
Valid N (listwise)	18

1. Set up 95% confidence interval estimate for the averagesatisfactory level in 2003.

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1. Supposing the population standard deviation of satisfactory levels in2003 is equal to1, what sample size is required if the Margin of Error is 0.2 at 95% of confidence for the estimate of the averagesatisfactory level in 2003?

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1. Is there evidence that mean satisfactory level in 2003 is different from 6 at =0.05?

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1. Supposing the population variances of satisfactory in2003 and 2005 are equal,is there evidence that mean satisfactory level in 2003 is different from that in 2005 at =0.05?

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1. Supposing the population variances of satisfactory in2003 and 2004 are not equal,is there evidence that mean satisfactory level in 2003 is different from that in 2004 at =0.05?

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